Variable flow resistance for use with a subterranean well

Abstract

A variable flow resistance system for use with a subterranean well can include a structure which displaces in response to a flow of a fluid composition, whereby a resistance to the flow of the fluid composition changes in response to a change in a ratio of desired to undesired fluid in the fluid composition. Another system can include a structure which rotates in response to flow of a fluid composition, and a fluid switch which deflects the fluid composition relative to at least two flow paths. A method of variably resisting flow in a subterranean well can include a structure displacing in response to a flow of a fluid composition, and a resistance to the flow of the fluid composition changing in response to a ratio of desired to undesired fluid in the fluid composition changing. Swellable materials and airfoils may be used in variable flow resistance systems.

1 . A variable flow resistance system for use with a subterranean well, the system comprising:
 a structure which displaces in response to a flow of a fluid composition, whereby a resistance to the flow of the fluid composition changes in response to a change in a ratio of desired to undesired fluid in the fluid composition.   
     
     
         2 . The system of  claim 1 , wherein the structure is exposed to the flow of the fluid composition in at least first and second directions, and wherein the resistance to the flow changes in response to a change in a proportion of the fluid composition which flows in the first and second directions. 
     
     
         3 . The system of  claim 1 , wherein the structure is more biased in a first direction by the flow of the fluid composition more in the first direction, and wherein the structure is more biased in a second direction by the flow of the fluid composition more in the second direction. 
     
     
         4 . The system of  claim 3 , wherein the first direction is opposite to the second direction. 
     
     
         5 . The system of  claim 3 , wherein the first and second directions comprise at least one of the group including circumferential, axial, longitudinal, lateral, and radial directions. 
     
     
         6 . The system of  claim 1 , further comprising a fluid switch which directs the flow of the fluid composition to at least first and second flow paths. 
     
     
         7 . The system of  claim 6 , wherein the structure is more biased in a first direction by the flow of the fluid composition more through the first flow path, and wherein the structure is more biased in a second direction by the flow of the fluid composition more through the second flow path. 
     
     
         8 . The system of  claim 6 , wherein the structure pivots, and thereby varies the resistance to flow, in response to a change in a proportion of the fluid composition which flows through the first and second flow paths. 
     
     
         9 . The system of  claim 6 , wherein the structure rotates, and thereby varies the resistance to flow, in response to a change in a proportion of the fluid composition which flows through the first and second flow paths. 
     
     
         10 . The system of  claim 6 , wherein the structure rotates, and thereby varies the resistance to flow, in response to the change in the ratio of desired to undesired fluids. 
     
     
         11 . The system of  claim 6 , wherein the fluid switch comprises a blocking device which at least partially blocks the flow of the fluid composition through at least one of the first and second flow paths. 
     
     
         12 . The system of  claim 11 , wherein the blocking device increasingly blocks one of the first and second flow paths, in response to the flow of the fluid composition toward the other of the first and second flow paths. 
     
     
         13 . The system of  claim 11 , wherein the fluid switch directs the flow of the fluid composition toward one of the first and second flow paths in response to the blocking device increasingly blocking the other of the first and second flow paths. 
     
     
         14 . The system of  claim 1 , further comprising an airfoil which deflects the flow of the fluid composition in response to the change in the ratio of desired to undesired fluid. 
     
     
         15 . The system of  claim 1 , further comprising a material which swells in response to a decrease in the ratio of desired to undesired fluid, whereby the resistance to flow is increased. 
     
     
         16 . The system of  claim 1 , wherein the resistance to flow decreases in response to an increase in the ratio of desired to undesired fluid. 
     
     
         17 . The system of  claim 1 , wherein the resistance to flow increases in response to a decrease in the ratio of desired to undesired fluid. 
     
     
         18 - 49 . (canceled) 
     
     
         50 . A method of variably resisting flow in a subterranean well, the method comprising:
 a structure displacing in response to a flow of a fluid composition; and   a resistance to the flow of the fluid composition changing in response to a ratio of desired to undesired fluid in the fluid composition changing.   
     
     
         51 . The method of  claim 50 , further comprising exposing the structure to the flow of the fluid composition in at least first and second directions, and wherein the resistance to the flow changing further comprises the resistance to the flow changing further in response to a change in a proportion of the fluid composition which flows in the first and second directions. 
     
     
         52 . The method of  claim 50 , further comprising the structure being increasingly biased in a first direction by the flow of the fluid composition increasingly in the first direction, and the structure being increasingly biased in a second direction by the flow of the fluid composition increasingly in the second direction. 
     
     
         53 . The method of  claim 52 , wherein the first direction is opposite to the second direction. 
     
     
         54 . The method of  claim 52 , wherein the first and second directions comprise at least one of the group including circumferential, axial, longitudinal, lateral, and radial directions. 
     
     
         55 . The method of  claim 50 , further comprising a fluid switch directing the flow of the fluid composition toward at least first and second flow paths. 
     
     
         56 . The method of  claim 55 , further comprising the structure being increasingly biased in a first direction by the flow of the fluid composition increasingly through the first flow path, and the structure being increasingly biased in a second direction by the flow of the fluid composition increasingly through the second flow path. 
     
     
         57 . The method of  claim 55 , wherein the structure displacing further comprises the structure pivoting, and thereby varying the resistance to flow, in response to a change in a proportion of the fluid composition which flows through the first and second flow paths. 
     
     
         58 . The method of  claim 55 , wherein the structure displacing further comprises the structure rotating, and thereby varying the resistance to flow, in response to a change in a proportion of the fluid composition which flows through the first and second flow paths. 
     
     
         59 . The method of  claim 55 , wherein the structure displacing further comprises the structure rotating, and thereby varying the resistance to flow, in response to the change in the ratio of desired to undesired fluids. 
     
     
         60 . The method of  claim 55 , further comprising a blocking device of the fluid switch at least partially blocking the flow of the fluid composition through at least one of the first and second flow paths. 
     
     
         61 . The method of  claim 60 , wherein the blocking device increasingly blocks one of the first and second flow paths, in response to the flow of the fluid composition toward the other of the first and second flow paths. 
     
     
         62 . The method of  claim 60 , wherein the fluid switch directs the flow of the fluid composition toward one of the first and second flow paths in response to the blocking device increasingly blocking the other of the first and second flow paths. 
     
     
         63 . The method of  claim 60 , further comprising an airfoil deflecting the flow of the fluid composition in response to the ratio of desired to undesired fluid changing. 
     
     
         64 . The method of  claim 50 , further comprising a material swelling in response to the ratio of desired to undesired fluid decreasing, and wherein the resistance to the flow changing further comprises the resistance to the flow increasing in response to the material swelling. 
     
     
         65 . The method of  claim 50 , wherein the resistance to the flow changing further comprises the resistance to the flow decreasing in response to the ratio of desired to undesired fluid increasing. 
     
     
         66 . The method of  claim 50 , wherein the resistance to the flow changing further comprises the resistance to the flow increasing in response to the ratio of desired to undesired fluid decreasing.